Th e North American species of Lasionycta Aurivillius are revised to include 43 species and 13 subspecies using traditional methods and mitochondrial cytochrome oxidase subunit 1 (CO1) DNA sequence (barcode) analysis. Seven species-groups are recognized, and one group is further divided into seven subgroups. Seventeen species and six subspecies of Lasionycta are described: Adults and genitalia of all North American Lasionycta and Psammopolia species and the new Tricholita are illustrated. Keys to species-groups and species are presented. DNA barcodes of 39 of the 43 species were sequenced and are presented as neighbor-joining phylograms. Th e barcodes support the taxonomy at genus and species-group level, but not consistently at the sub-group level. At the species-level, performance of DNA barcodes was variable; 17 of the 39 barcoded species exhibited haplotype variation discordant with morphology, phenotype and distribution. A high frequency (43.6 %) of haplotypes were either shared among more than one species (representing eight species), or were closely similar and nested within haplotypic variation of other species (nine species).